Clutch discs with rubbers separators

ABSTRACT

A multiple disc clutch pack for transmitting and interrupting power flow between a drive member and a driven member. Alternating discs axially shiftable, but nonrotatably secured to one of the members, have elastomeric elements extending into engagement with adjacent discs on the said member to separate the discs when the power flow therethrough is interrupted, and are compressible to permit frictional engagement of all the discs when the power is being transmitted.

[56] References Cited UNITED STATES PATENTS 3,455,423 7/1969Lindquist..................... 192/107 FOREIGN PATENTS 614,913 12/1948Great Britain................ 192/7028 Primary Examiner- Benjamin W.Wyche AttorneyNoelG. Artman ABSTRACT: A multiple disc clutch pack fortransmitting and interrupting power flow between a drive member and adriven member. Alternating discs axially shiftable, but nonrotatablysecured to one of the members, have elastomeric elements exo UnitedStates Patent [72] Inventors Nils-Eric G. Bark Lake Bluff; Karl Kordas,Mundelein, both of, ll]. 21 Appl. No. 837,146 [22] Filed June 27, 1969[45] Patented June 15, 1971 [73] Assignee International HarvesterCompany Chicago, Ill.

[54] CLUTCH DISCS WITH RUBBERS SEPARATORS 3 Claims, 3 Drawing Figs.

pressible to permit n the power is being 1.1 5. 5 kccuisihi Bertha:

tending into engagement with adjacent discs on the said member toseparate the discs when the therethrough is interrupted, and are comfrictional engagement of all the discs whe transmitted.

CLUTCH DISCS WITH RUBBERS SEPARATORS BACKGROUND AND SUMMARY OF THEINVENTION Conventi nal clutch packs encounter two problems. When theclutch pack is free spinning, i.e. not transmitting power, the discstend to drag on each other and build up heat. To some extent this can becompensated by flooding the pack with cooling oil. The second problem isone termed flutter failure." The drum which supports one set of platesor discs tends to wobble relative to the shaft which supports the otherset of discs. While the exact cause of the wobble is not definitelyestablished, it is believed that the tolerances in the bearingsrotatably mounting the drum is the significant factor. Whatever thereason, it is known that for a given geometry clutch pack, the discswill become excited and tend to flutter at certain speeds when theclutch is free spinning. When the discs flutter, they do not remainparallel to each other and hence come into spot or point contact withadjacent discs. Such small areas of contact concentrates the heatbuildup and often flooding with cooling oil is insufficient to preventburning of the discs in these areas. Severe cases of flutter can elevatethe temperature in the areas of contact sufficiently high to actuallyweld the plates together.

Many attempts have been made to provide a means for separating theplates during free spinning. All of the prior art clutch packseparators, however, have sufiered from at least one of the followingdeficiencies: restricting or sacrificing frictional area; requiringmoving contact between the'separator and the discs during free spinning;imposing a frictional load on the lining material from the separatorduring free spinning; or have utilized a separator having a physicalarrangement and located such that it is capable of damaging the liningmaterial on the discs.

It is therefore an object of this invention to provide a separator for aclutch pack which does not sacrifice frictional area, which does notrequire movinglcontact between the separator and the disc; which doesnot come into contact with the frictional lining material, and which isincapable of damaging the discs in the event of failure of theseparator.

It is also an object of this invention to provide a method forinstalling a separator in a disc of a clutch pack.

It is a further object of this invention to provide a separator which iseasy to install and which will provide a long service life.

FIG. I is a cross-sectional view of a portion of a clutch packincorporating the present invention,

FIG. 2 is a plan view of a single disc, with a portion broken away,showing the spacer of the present invention secured thereto, and

FIG. 3 is a cross-sectional view, to a larger scale, taken on lines 33of FIG. 2.

PREFERRED EMBODIMENT OF THE INVENTION Since it is intended that thepresent invention may be incorporated into conventional clutch packsalready in production, FIG. 1 illustrates a portion of such aconventional clutch pack, indicated generally at 10. An outer member ordrum 12 is mounted in bearings, (not shown), for rotation about the axis14. An inner sleeve or shaft 16 is also journaled for rotation about theaxis 14. One of the members 12 and 16 is the driving member and theother is the driven member. The shaft member 16 is provided with anexternal spline 18 which permits the mounting of a plurality of plates20. The plates 20 are provided with internal diameters having a shapecomplementary with the spline 18 and mount on the spline 18 so that theplates are axially shiftable, but nonrotatable relative to the member16. Frictional material 22 is secured to each face of the plates 20.Typically, the plate 20 is formed of a steel material and the facing offrictional material 22 is formed of sintered bronze. Interleaved betweenthe plates 20 are a plurality of discs 24. Each disc is provided with aplurality of tangs 26, as shown in FIG. 2, which tangs are engageablewith complementary slots 28 formed on the interior of the drum 12. Theengagement of the tangs 26 with the slots 28 permit the axial shiftingof the discs 24 relative to the drum 12 while prohibiting relativerotation between the two. An actuator means 30, which customarily takesthe form of a hydraulically actuated piston means, is moveable betweenthe disengaged position, such as shownin FIG. 1, wherein the discs arefree to rotate relative to the plates, and an engaged position whereinthe plates and discs are forced into frictional engagement. In theengaged position power will be transmitted between the two members 12and 16, whereas in the disengaged position power flow between the twomembers will be interrupted.

A separator or spacer 32 is provided on every other one of the discs.These spacers are made of an elastomeric material capable ofwithstanding high temperature levels, such as fluorocarbon rubber, whichis sold by DuPont under the trademark Viton.

In order to preclude cocking or side tilting of the discs, it isdesirable to install a plurality of such spacers on each one of thealternate discs equipped with spacers and to locate the spacers so thatthey are equiangularly arranged around the periphery of the discs, asshown in FIG. 2. The tang 26 of each disc does not make any contributiontoward the friction engagement between the discs 26 and the plates 24,and hence it is highly advantageous to position the spacers 24 on thetang 26.

In this location, the spacers do not diminish the contact area availablefor frictional engagement. Each spacer 32 extends from the free surfaceof each alternating disc into contact with the adjacent disc. Since thediscs 24 are all moveable in rotation unison with the drum 12, there isno relative movement between the discs 24, and hence, there is norelative rotational movement between the free end of the spacer and theadjacent disc. Each spacer extends beyond the side of the disc to whichit is attached by an amount at least equal to the thickness of theadjacent plate 20 and preferable to insure minimum drag during freespinning, should extend from the side of the supporting disc a distancebetween 0.014 to 0.024 inch greater than the adjacent plate's thickness.

When the actuator means 30 moves to the right, as viewed in FIG. 1, toengage the clutch pack, the discs and plates will be forced into tightcontact. This will cause the elastomeric material to be compressed. Asthis material is compressed, each spacer will be shortened in length andincreased in diameter or buttoned up." To make sure that the adjacentplates do not cut the spacers under this buttoned up" condition, eachspacer must be positioned radially on the tang a distance sufficient topreclude contact with the plates under the maximum increased diameterconditions. That is, allowing for the maximum permissible wear on theplates and discs, which creates conditions for maximum increase indiameter of the spacer, the spacer should be positioned radially outwardon the tang a distance sufficient to clear the plates.

While the spacers may take a variety of shapes and may be secured to thetang in a variety of ways, it is preferred that the spacer have theshape of a cylinder of substantially constant diameter, in its relaxedstate, and that it be secured to the tang by trapping it in an openingin the tang of smaller diameter than the cylinder. As shown in FIG. 3,the spacer 32 has the form of a cylinder with a diameter 34. The opening36 formed in the tang 26 has a diameter 38 which is smaller than thediameter 34. The difference in diameter need not be substantial becausethe button up" effect resulting from compression of the plates,increases the diameter of the cylinder even more and tends to hold thecylinder within the opening 36. A bevel or chamfer 40 is formed on eachend of the opening 36 to minimize the possibility of the spacer beingcut when it is buttoned up during compression.

The placement of the cylindrical spacer 32 in the opening 36is achievedin the following manner.

A taper is formed on one end of a cylindrical rod of elastomericmaterial; the taper being sufficiently long to permit it to be insertedthrough the opening 36 and grasped on the other side. Once the taperedportion is grasped, a tension force is applied to the rod, which forcemust be sufficient to elongate the rod and reduce its diameter to besubstantially equal to the diameter of the opening 36. While the rod isso tensioned, it is moved axially of the opening 36 to a position inwhich a full diameter portion extends a substantial distance on eitherside of the disc 24. The tension force can then be relaxed and the rodcut to provide a full diameter cylinder portion extending from each sideof the disc a distance at least equal to the thickness of the adjacentplate and preferably 0.014 to 0.024 inch greater than that platesthickness.

While applicant has shown and described one form the invention may takeand has described one method for assembling it, it is to be understoodthat various modifications may be made in either the structure or themethod without departing from the spirit of the invention.

What we claim is: g

1. in a clutch pack for transmitting and interrupting power flow betweenan outer drum means and a shaft means mounted for rotation about acommon axis, said drum means having a plurality of axially extendingslots, and said shaft means having an external spline, a plurality ofdiscs having tangs engageable with the slots and a plurality of plateshaving a toothed inner diameter engageable with the spline, said discsand plates being alternately interleaved, and actuating means forselectively forcing said discs plates into frictional engagement andpermitting said discs and plates to rotate relative to each other; theimprovement comprising:

every other one of said discs having at least one opening extendingtherethrough;

a spacer positioned in each of said openings and consisting of acylindrical member of elastomeric material having a constant diameter inits relaxed state larger than the diameter of said opening;

each of said spacers being retained within the opening solely by theforced constriction of an intermediate portion of the cylindrical memberby the smaller diameter opening.

2. In a clutch pack according to claim 1, wherein the outer ends of eachopening are provided with a chamfer, whereby compression of thecylindrical member under power trans mitting conditions will precludecutting said member.

3. In a clutch pack according to claim 2, wherein each spacer extendsfrom the side of the disc in which it is retained a distance which isbetween 0.014 and 0.024 inch greater than the thickness of the adjacentplate, whereby viscous drag between plates and discs is minimized whenthe clutch pack is in a free running position.

1. In a clutch pack for transmitting and interrupting power flow betweenan outer drum means and a shaft means mounted for rotation about acommon axis, said drum means having a plurality of axially extendingslots, and said shaft means having an external spline, a plurality ofdiscs having tangs engageable with the slots and a plurality of plateshaving a toothed inner diameter engageable with the spline, said discsand plates being alternately interleaved, and actuating means forselectively forcing said discs plates into frictional engagement andpermitting said discs and plates to rotate relative to each other; theimprovement comprising: every other one of said discs having at leastone opening extending therethrough; a spacer positioned in each of saidopenings and consisting of a cylindrical member of elastomeric materialhaving a constant diameter in its relaxed state larger than the diameterof said opening; each of said spacers being retained within the openingsolely by the forced constriction of an intermediate portion of thecylindrical member by the smaller diameter opening.
 2. In a clutch packaccording to claim 1, wherein the outer ends of each opening areprovided with a chamfer, whereby compression of the cylindrical memberunder power transmitting conditions will preclude cutting said member.3. In a clutch pack according to claim 2, wherein each spacer extendsfrom the side of the disc in which it is retained a distance which isbetween 0.014 and 0.024 inch greater than the thickness of the adjacentplate, whereby viscous drag between plates and discs is minimized whenthe clutch pack is in a free running position.